One computer (RPi CM4), 2 NICs, two separate networks

3 min read 28-10-2024

the ifix

One computer (RPi CM4), 2 NICs, two separate networks

In this article, we will explore how to configure a Raspberry Pi Compute Module 4 (RPi CM4) equipped with two Network Interface Cards (NICs) to operate on two separate networks. This setup can be beneficial for a variety of applications, including home automation, development environments, and networking projects.

Problem Scenario

Original Problem Statement: "One computer (RPi CM4), 2 NICs, two separate networks."

Revised Statement: "How can I configure a Raspberry Pi Compute Module 4 with two Network Interface Cards to operate on two distinct networks?"

Configuration Overview

Before diving into the configuration, let's clarify the components involved:

Raspberry Pi Compute Module 4 (RPi CM4): This is a powerful version of the Raspberry Pi that provides enhanced performance and flexibility.
Two Network Interface Cards (NICs): These can either be USB NICs or the built-in Ethernet port, depending on your use case.
Two Separate Networks: This configuration allows one NIC to connect to a local network (LAN) while the other connects to a different subnet or external network.

Practical Example

Requirements

To set up the Raspberry Pi CM4 with two NICs on two separate networks, you will need:

Raspberry Pi Compute Module 4
Two NICs (USB or onboard Ethernet)
A power supply
MicroSD card with Raspberry Pi OS installed
Access to a monitor and keyboard (or SSH for remote access)

Step-by-Step Configuration

Install the Raspberry Pi OS: If you haven't already, install the Raspberry Pi OS on your microSD card. You can use the official Raspberry Pi Imager for this.
Connect NICs: Attach both NICs to the Raspberry Pi. Ensure that they are recognized by the system by running:
```
lsusb
```
Check Network Interfaces: Use the ifconfig command to see the available network interfaces. Typically, you will see eth0 for the onboard NIC and eth1 for the USB NIC.
Assign IP Addresses:
- For the First NIC (eth0): Connect it to the local network (e.g., DHCP-enabled).
```
sudo dhclient eth0
```
- For the Second NIC (eth1): Assign a static IP address.
```
sudo ifconfig eth1 192.168.2.2 netmask 255.255.255.0
```
Configure Routing: You may need to configure routing rules to ensure that traffic flows correctly between the two networks. Use the route command to add routes as necessary.

Example Configuration

Assuming you want your Raspberry Pi to connect to two different networks:

Network A: 192.168.1.0/24 (connected via eth0)
Network B: 192.168.2.0/24 (connected via eth1)

You can set up routing with the following command:

sudo route add -net 192.168.2.0 netmask 255.255.255.0 gw 192.168.1.1

In this example, 192.168.1.1 is the gateway for Network A.

Additional Considerations

Firewall Rules: Depending on your use case, consider setting up firewall rules using iptables to control the traffic between the two networks.
Performance Monitoring: Use tools like iftop or vnstat to monitor the network traffic on both interfaces for better insight.
Automating Configuration: Consider using scripts or tools like NetworkManager or systemd-networkd for automatically managing your network interfaces on boot.

Conclusion

Setting up a Raspberry Pi CM4 with two NICs for separate networks is an excellent way to enhance your networking capabilities. Whether you're isolating networks for security purposes or improving your home automation system, this configuration provides flexibility and efficiency.

Useful Resources

By following these guidelines, you can successfully manage two separate networks on your Raspberry Pi, enhancing your project's capabilities and efficiency. Happy networking!